The recent rapid progress in standardization of a new high-density optical disc, for example, a BD-RE (Blu-ray Disc-Rewritable), capable of recording high-quality video data and high-quality audio data for a lengthy period of time has led to anticipation that the associated products will be developed and commercially available.
The BD-RE has, as shown in FIG. 1, a clamping area, transition area, burst cutting area (BCA) and lead-in area defined sequentially at the inner periphery thereof, and a data area and lead-out area defined respectively at the intermediate portion and outer periphery thereof.
The lead-in area is partitioned into a first protection zone Protection zone 1, a PIC (Permanent Information & Control data) zone, a second protection zone Protection zone 2, an information 2 zone Info 2, an optimum power control (OPC) zone, etc. Whereas the first protection zone and PIC zone are pre-recorded areas where data is pre-recorded in advance, the remaining zones of the lead-in area, the data area and the lead-out area are rewritable areas where new data is rewritten.
High frequency modulated (HFM) grooves are formed in the PIC zone, in which main information of the disc to be permanently preserved is stored. These HFM grooves are modulated by a bi-phase modulation method to store disc information (DI), as shown in FIG. 2.
HFM Grooves is modulated in the radial direction with a rather high bandwidth signal, to create a data channel for replicated information with sufficient capacity and data rate. As shown in FIG. 2, encoding data into a wobbled groove can be performed by the bi-phase modulation.
In the modulation method, a bit with value 0 may be represented by a transition at the start of the bit cell and a bit with value 1 may be represented by a transition at the start and in the middle of the bit cell. The modulated bits may be recorded on the disc by a deviation of the groove from its average centerline as indicated in FIG. 2. The length of each bit cell may be 36T, where T corresponds to the length of a channel bit in the rewritable data areas.
Meanwhile, the standardization of a new read-only high-density optical disc, as well as the BD-RE, is recently under discussion among the associated companies.
The new read-only high-density optical disc may be, for example, a BD-ROM, which has, as shown in FIG. 3, an inner area, clamping area, transition area, information area and rim area. The information area includes a data zone where main data, such as an A/V stream, is recorded while being encrypted by CPI (Copy Protection-related Information) for illegal copy protection. The information area further includes a PIC zone for recording the CPI and DI. Therefore, an optical disc device detects the CPI recorded in the PIC zone in initial servo operation, and then reproduces the main data encrypted and recorded in the data zone while decrypting it using the detected CPI.
However, it may be possible to illegally store the BD-ROM data stream decrypted and reproduced by the optical disc device in a storage medium, such as a hard disk drive (HDD) of a personal computer, and illegally make a BD-ROM without CPI using a BD-ROM formatter and mastering machine. In this case, since the illegally made BD-ROM has no CPI, but is recorded with the decrypted data stream, it becomes the same as a legally made BD-ROM that has no CPI and is recorded with an unencrypted data stream. For this reason, it is not possible to make a distinction between the legally made BD-ROM and the illegally made BD-ROM. However, there is currently no efficient solution to such a problem.